Jenny is still smitten with Alec, her colleague Chummy is adjusting to motherhood and Shelagh (the former Sister Bernadette) is facing life without her nun’s habit but with a fiancé in that nice Doctor Turner.

Yet it’s not all festive births, cheery nativity plays and carols around the piano. This year, the midwives’ Christmas celebrations are interrupted by the discovery of an unexploded Second World War bomb in the neighbourhood.

“A couple of bombs were found in the east end in those years so it was in the news, it was happening,” explains Helen George, who plays bubbly midwife Trixie.

This shocking discovery means Christmas preparations are forgotten – tinsel discarded, pinwheel sandwiches abandoned – as the residents of Poplar find themselves under threat. “Everyone is thrown into a bit of a tiz-woz because it happens at three in the morning,” reveals Jessica Raine (the usually calm and collected Jenny). “Suddenly PC Noakes is knocking on the door!”

The midwives soon jump into action, guiding the community to safety. “Nonnatus House is really called upon,” says Raine, “because the nuns and nurses know the community so well. They are the first ones at the rescue centre and they get it ready for the surge of people who have been evacuated.”

While the bomb is investigated, it’s the midwives’ job to keep everyone calm. Well, that and make sure there are lots of tea and biscuits constantly available! “Basically just making tea…” says George. “Lots of tea.”

But we all know there is more to Call the Midwife than tea and biscuits – it wouldn’t be a right if the episode passed without a few shed tears.

These come in the form of a two troubling storylines, which personally affect the girls themselves and reveal a bit more about the women who drive the drama.

“We are afforded a bit more back story,” Raine tells us, “which is fascinating, because you want to know more about these girls.”

It does make you realise just how little we actually know about the girls’ pasts – hopefully, the shift signals a change of focus that will shine more of a light on the midwives themselves in series three.

While the Christmas special does bring darkness, as ever, there’s also light. Jenny is bright, fun and flirty with new squeeze Alec – Raine told us she hopes a “naughtier” side to the sensible midwife will be revealed in the coming series, and we have to say we agree.

There’s also a feeling that however Christmas is interrupted it’s important to remember that the festivities are really about loved ones, whether they are your dishy new boyfriend, your loving wife or the people who work alongside you day after day.

Which is all good and well, we hear you say, but the big question does still remain…